The date March 22, 1988 was chosen because the moon occulted stars within the pleides as visible from North America.
NOTE: This diagram is geometrically accurate, although not physically possible to see since the moon was not actually above the horizon in half the views. Specifically you can never see the Pleiades from the south pole! They were just picked as extreme views from the earth, the limit of what might be seen from a set of four locations in a square on a great circle and a moon just above the horizon in all four locations.
Example of lunar parallax from 4 points on earth This is a simulated image, combining of 4 views of the sky and the moon's location relative to the background stars at a single point in time. The bright stars visible are the [[open cluster|star cluster]